BMS-986001 is a novel thymidine nucleoside reverse transcriptase inhibitor. This phase IIa dose-escalating study investigated 10 days of monotherapy of 4 doses of BMS-986001 in a double-blind design. Thirty two experienced HIV-1 infected patients, with no treatment for more than 3 months,  were randomised to BMS-986001 at different doses (100, 200, 300, 600 mg) or placebo once-daily (6 subjects on BMS-986001 and 2 on placebo for each treatment groups). Tolerability and safety was good, with no dose-related adverse event and no discontinuation for adverse events. Most adverse events were mild and were judged not related or probably not related to BMS-986001. Antiviral activity, assessed by median decrease in plasma HIV-1 RNA from baseline to day 11, was seen for all doses of BMS-986001 : -0.97, -1.15, -1.28, and -1.15 log10 copies/mL at 100, 200, 300, and 600 mg, respectively. The pharmacokinetics were dose proportional and plasma area under the curve correlated with the antiviral activity of BMS-986001.